More specifically, this invention is directed to improved lock systems and, especially, to improved cylinder locks and cooperating keys therefor.

Accordingly, the general objects of the present invention are to provide novel and improved methods and articles of such character.

(2) Description of the Prior Art Mechanical locks which employ one or more linear arrays of pin tumblers are, of course, well known in the art. The pin tumblers, i.e., the stacks of cooperating tumbler pins, of such locks are linearly displaceable, typically radially relative to the axis of rotation of a plug or core, in response to insertion of a key in a keyway provided in the core. The pin tumblers are comprised of at least an upper or driver pin, which is spring biased toward the axis of core rotation, and a driven or bottom pin which is axially aligned with the driver pin when the lock is in the locked state. The pin tumblers are received in chambers provided in the core and shell of the lock, the pin chambers in the core being in communication with the keyway of the lock and the outer circumference of the core. The pin tumbler receiving chambers of the core and shell are also in axial alignment with the lock in the locked state. A properly bitted key will, through communication with bottom pins in the pin chambers in the core, produce pin tumbler displacement which causes an interface between pins of each of the pin tumblers to be coincident with a shear line defined by the core outer circumference. Thus, a properly bitted key will permit the core, with the bottom pins, to rotate within the shell. Core rotation will, through the action of a cam or tail piece coupled thereto, cause operation of a latch or other similar locking mechanism.

Locks of the type generally discussed above are known in the art as "cylinder" locks. The most common manner of defeating a cylinder lock consists

of "manufacture" of an unauthorized key. It is believed fair to state that it is not possible to ensure against lock defeat simply by designing an intricate keyway, i.e., a keyway having a complex profile, and/or through the use of various arrangements of pin tumblers. Rather, a high level of security dictates that the lock manufacturer have the ability to exercise key control by being the sole authorized source of key blanks which may be employed as the key portion of the system.

Summary of the Invention The present invention overcomes the above-briefly discussed and other deficiencies and disadvantages of the prior art and, in so doing, provides a novel lock system which includes a key with a blade having unique physical characteristics. This unique key blade cooperates with one or more auxiliary locking pins which are provided in the lock core.

A lock system in accordance with the invention includes a cylinder lock with a rotatable core which carries at least one reciprocal auxiliary locking pin.

As used herein, the term "pin" is intended to describe a single member or a plurality, i.e., a stack, of pin segments. In the locked condition of the system, the auxiliary locking pin is resiliently biased away from the keyway and across the shear line of the lock so as to engage the shell, such engagement typically being established by insertion of the outer end of the auxiliary pin into a chamber, i.e., a cooperating recess, provided in the shell. The auxiliary locking pin thus aids in inhibiting relative movement between the core and shell. The auxiliary locking pin is reciprocal along an axis which is generally transverse to a plane defined by the keyway. The axis of movement of the auxiliary locking pin preferably does not intersect the axis of core rotation, i.e., the auxiliary locking pin is displaced from a line through the center of the cylinder lock. At its opposite inner end, the auxiliary locking pin is provided with a shaped head portion which at all times extends into the keyway from a side thereof. This shaped head portion includes a reaction surface against which a force directed axially with respect to the auxiliary pin may be applied.

The lock system of the invention further includes a key which is provided, in the side of the blade which faces in the direction of the auxiliary locking pin, with a longitudinal slot sized and shaped to cooperate with the head portion of the auxiliary locking pin. In a first region extending longitudinally from the blade tip toward the bow, wall(s) of the longitudinal slot which are generally complementary in shape and juxtapositioned to the auxiliary locking pin reaction surface have a first average displacement from the side of the keyway through which the auxiliary locking pin extends. This first average displacement is selected such that the shaped head portion of the auxiliary locking pin will be loosely received in the slot at the blade tip. The key blade slot wall(s) which face the auxiliary locking pin reaction surface, in a second longitudinal region displaced from the blade tip, have a second greater average displacement from the side of the keyway. This second displacement is commensurate with engagement of the auxiliary locking pin head portion and application of an axial force thereto which exceeds and is directed oppositely to the resilient bias. The maximum displacement of the complementary shaped wall(s) of the longitudinal slot second portion is, in a preferred embodiment, insufficient to fully withdraw the auxiliary locking pin from the cooperating recess in the shell. The coaction between the slot wall(s) in the second longitudinal portion of the slot and the auxiliary locking pin reaction surface will produce sufficient displacement of the auxiliary locking pin to enable rotation of the core relative to the shell to at least be initiated. In the preferred embodiment, however, the auxiliary locking pin will be only partially withdrawn from the shell recess by the cooperation between the key slot second portion and pin reaction surface. Accordingly, sufficient relative rotation between the core and shell to operate the lock from the locked to the unlocked state will still not be permitted.

In the preferred embodiment, the second end of the auxiliary locking pin is shaped to cooperate with a shaped wall at one side of the shell recess in the manner of a cam follower and cam. Accordingly, when enabled by partial pin withdrawal, the initial rotation of the core relative to the shell will, through camming action, produce further axial displacement of the auxiliary locking pin in a direction which will tend to cause the auxiliary locking pin to move

completely out of engagement with the shell recess. Such further axial movement of the auxiliary locking pin requires that the key be bitted or coded such that movement of the auxiliary locking pin head portion laterally with respect to the longitudinal slot second portion is enabled. Such enablement is achieved by providing the head portion of the auxiliary locking pin with an extension which normally abuts the base of the longitudinal slot in the key blade. This extension is sized and shaped to be received in an opening, preferably an aperture, provided in the base of the key blade slot in the second region thereof. When this further code condition is met, i.e., when the auxiliary locking pin head extension can pass into a properly located and complementary shaped opening, the partially withdrawn auxiliary locking pin may be cammed out of locking engagement with the shell recess subsequent to partial withdrawal of the auxiliary locking pin and also subsequent to displacement of the pin tumbler stacks of the lock to the unlocked condition by the other, i.e., conventional, bitting on the blade.

A key of a locking system in accordance with the present invention must, accordingly, be provided with a properly shaped longitudinal slot or groove which will coact with the head of a locking pin to apply a pulling force to the pin, that longitudinal slot must have at least two linear portions wherein the average displacement from a keyway side of a surface provided to engage and coact with an auxiliary locking pin reaction surface is different, the blade must have a profile in addition to the longitudinal slot which is commensurate with the keyway of the lock and the blade must be bitted on the appropriate surface(s) so as to cooperate with the primary pin tumblers of the lock. Further, in the preferred embodiment, the blade must be provided with a properly shaped and located recess or aperture in that portion of the slot where axial forces are being applied to the auxiliary locking pin.

In accordance with a preferred embodiment of the invention, the head portion of the auxiliary locking pin and the cooperating slot in the side of the key blade respectively constitute a tenon and mortise.

Brief Description of the Drawing The present invention may be better understood, and its numerous objects and advantages will become apparent to those skilled in the art, by reference to the accompanying drawing, wherein like reference numerals refer to like elements in the several Figures and in which: Figure 1 is a side elevation view, partly broken away to reveal detail, of a preferred embodiment of a lock system in accordance with the present invention; Figure 2A is a side elevation view of a preferred embodiment of a key blank from which the key of the lock system of Figure 1 may be formed by producing the cuts which define the bitting; Figure 28 is a cross-sectional top plan view, taken along line 2-2 of Figure 2, of the blade portion of the key blank of Figure 2A; Figure 3 is a cross-sectional, schematic side-elevation view of the lock of Figure 1 without a key present in the keyway; Figure 4A is a view similar to Figure 3 but with an authorized key partly inserted in the keyway; Figure 48 is a view taken along line 4-4 of Figure 4A; Figures 5A and 5B are views respectively identical to Figures 4A and 4B but with the key fully inserted in the keyway; Figures 6A and 6B are respectively views identical to Figures 5A and 5B but with the lock core rotated relative to the shell; and Figure 7 is an enlarged side elevation view of the auxiliary locking pin of the lock of Figures 1 and 3 - 6.

Description of the Preferred Embodiment The disclosed embodiment of the present invention will now be described with reference to the drawing. It is to be noted that conventional elements of the lock have been omitted from the drawing in the interest of facilitating understanding of the invention and that the various cross-sectional views of the lock are schematic illustrations rather than manufacturing drawings.

A lock system in accordance with the invention is indicated generally at 10 in Figure 1. The lock system is comprised of a cylinder lock, indicated generally at 12, and a cooperating key 14. Cylinder lock 12, as is conventional, comprises a core 16, see also Figures 3 - 6, which is rotatable about its longitudinal axis within and relative to a shell 18. The cylindrical boundary, i.e., the interface between core 16 and shell 18, defines the shear line or plane of the lock. The core 16 is provided with a keyway 20 having a profile, i.e., a cross- sectional shape, which is unique to the lock.

Referring to Figure 2A, a partially manufactured key 14, i.e., a key blank, has a bow portion 22 and a blade 24 which extends longitudinally from the bow and terminates at a tip. Blade 24 will be shaped, i.e., the initially flat side faces of the article from which the key blank of Figure 2A is formed will be milled, so that the profile of blade 24 matches the cross-sectional shape of keyway 20.

Accordingly, the key blade 24 may be inserted into the keyway.

As is also conventional, cylinder lock 12 will be provided with one or more arrays of reciprocally movable primary pin tumblers, the pin tumblers also sometimes being referred to as pin tumbler stacks. In the disclosed embodiment, the lock has a single linear array of pin tumblers. Referring to Figure 3, each pin tumbler will comprise at least a top or driver pin 26 and a bottom or driven pin 28. The pins comprising the pin tumblers are housed in pin tumbler chambers provided in the core 16 and shell 18. The chambers in the core and shell which receive a given pin tumbler stack will be in axial alignment when the lock is in the locked state. In the disclosed embodiment, the axes of the pin tumbler chambers are radially oriented with respect to the axis of rotation of core 16. The pin tumbler chambers in the core communicate with the keyway and, as shown in Figure 3, the bottom pins 28 of each pin tumbler extend into the keyway. In the disclosed embodiment of the invention, the pin tumblers are, in part, housed in an extension 30 of shell 18, such an extension being known in the art as a "bible". It will be understood that, in the locked condition, the pin tumblers are biased in the direction of the axis of rotation of core 16 by springs, not shown. Also in the locked condition of the cylinder lock, one of the pins of each pin tumbler extends across the shear line,

i.e., is partly in a chamber in each of the shell and core, and thus prevents rotation of the core relative to the shell. Rotation of the core relative to the shell is conventionally enabled by providing the key blade with bitting, i.e., surface irregularities, which engage the bottom pins and cause the pin tumblers to be displaced so that an interface between a pair of axially aligned pins is located on the shear line. In the embodiment disclosed, the key bitting would, as may be seen from Figure 1, be in the form of flat bottomed serrations provided in edge 32 of key blade 24. Cylinder lock 12 may have one or a plurality of arrays of pin tumblers, and the key bitting which cooperates with such pin tumblers may be on an edge(s) and/or side faces of the key blade and/or may take various forms and the axes along which the pins move do not have to be radially oriented with respect to the axis of core rotation.

In accordance with the present invention, and as best seen from Figures 3 - 6, cylinder lock 12 is provided with at least one auxiliary locking pin 40. Pin 40 is housed, for reciprocal motion, in a pin chamber 42 in core 16. Chamber 42 extends between a side of keyway 20 and the outer circumference of the core. Pin chamber 42 is provided with an inwardly extending rim or shoulder which functions as a seat for the first end of a biasing spring 44. The opposite end of biasing spring 44 coacts with a shoulder 45 on pin 40 (see Figure 7), i.e., spring 44 is in compression and surrounds a reduced diameter intermediate portion of pin 40. Spring 44 thus biases pin 40 outwardly, i.e., in a direction generally transverse to a plane defined by and extending through the center of keyway 20. The axes of the above-described primary pin tumblers, in the disclosed embodiment, lie in this plane. In contradistinction to the primary pin tumblers, the axis along which the auxiliary locking pin 40 moves does not, in the disclosed embodiment, intersect the axis of rotation of core 16. Auxiliary locking pin 40 is, accordingly, offset with respect to a center line of the core.

Referring to Figure 7, which is an enlarged view of auxiliary locking pin 40, at a first or inner end the pin includes a shaped head 46. Head 46, when viewed in cross-section in a plane transverse to the keyway, generally has the shape of a tenon which flares, i.e., enlarges, in the direction of the side of the keyway opposite to that through which pin 40 extends. Thus, the head 46 of

auxiliary locking pin 40, from the reduced diameter intermediate portion thereof, tapers outwardly. This tapered, i.e., frustoconical, portion of head 46 defines, as will be described below, a first reaction surface against which an axial force is applied. The first end of auxiliary locking pin 40, in the preferred embodiment, is further characterized by an extension 48 having a predetermined length, cross-sectional size and shape. In the disclosed embodiment, extension 48 is of cylindrical shape and is coaxial with pin 40.

The second, opposite end of auxiliary locking pin 40, i.e., the portion of pin 40 disposed on the shell side of the reduced diameter intermediate portion, releasably engages shell 18. This engagement may be accomplished by providing an opening 50, i.e., a recess, in the inner wall of shell 18. Referring jointly to Figures 48, 58, 6B and 7, the second end of pin 40 includes a projection 52 sized and shaped to engage recess 50. The outwardly facing side of projection 52, i.e., the end of pin 40 disposed oppositely with respect to extension 48, defines a second pin reaction surface 54 (Figures 6A and 7). In the preferred embodiment, in the manner to be described below, the provision of reaction surface 54 permits auxiliary locking pin 40 to function as a cam follower. Restated, axial motion may be imparted to pin 40 by means of the application of mechanical force to angled surface 54. With the lock in the locked state as represented by Figure 3, projection 52 is engaged in recess 50 and auxiliary locking pin 40 thus bridges the shear line of the lock and cooperates with the primary pin tumblers to prevent relative rotation between the core and shell. In this state, a pair of abutting walls 80 and 82, oriented generally parallelly with respect to the axis of pin 40 in the disclosed embodiment, respectively on the projection 52 and in recess 50, coact to prevent rotation of core 16 relative to shell 18.

Referring again to Figures 2A and 28, and also referring to Figures 4 - 6, the side 59 of blade 24 of key 14 which faces the side of the keyway through which auxiliary locking pin 40 extends is provided with a longitudinal slot 60.

Slot 60 has a shape which is generally complementary to that of head 46 of pin 40. Thus, extending longitudinally from the blade tip, blade 24 has a slot 60 which functions as a mortise which receives and coacts with the tenon defined

by the head 46 of auxiliary locking pin 40. The walls of key blade slot 60 which operatively engage the head of pin 40 have an average displacement from the side of the keyway, this displacement hereinafter being referred to as the operational slot depth. Slot 60 also has an overall depth measured between the base 61 of slot 60 and the outermost plane defined by side 59 of blade 24.

Slot 60 has a first overall depth and a first operational depth in a first linear section 62 thereof which extends inwardly from the blade tip. Slot 60 also includes, in the disclosed embodiment, a ramp 64 where both Its overall depth and operational depth transition from first or initial depths to second depths.

Slot 60 further has at least a third linear section 66 having the second overall and operational depths. In the preferred embodiment where pin 40 has a shaped head extension 48, an aperture 68 is provided in the base 61 of the key blade slot in linear portion 66. The size and shape of aperture 68 is complementary to the cross-sectional size and shape of extension 48 of head 46 of pin 40.

Figure 3 depicts the disclosed embodiment of a lock in accordance with the present invention in the locked state, i.e., without a properly configured and bitted key inserted in keyway 20. In this condition, the resilient bias of the primary pin tumblers causes the bottom pins 28 of the primary pin tumblers to extend into the keyway. The head 46 of auxiliary locking pin 40 also extends into the keyway. In the locked state of Figure 3, the second end of pin 40, namely the projection 52, is fully engaged in recess 50 in the wall of shell 18.

Thus, in the Figure 3 state, rotation of core 16 relative to shell 18 is prevented by the extension, across the shear line, of a pin of each of the primary pin tumblers and by the auxiliary locking pin 40. The head 46 of auxiliary locking pin 40, in the preferred embodiment, normally extends into the keyway to a position where it does not cross the center plane of the keyway.

When an authorized key is started into keyway 20, as represented in Figures 4A and 4B, the head portion 46 of pin 40 will be received in the first section 62 of key blade slot 60. The first overall and operational depths of slot 60 are selected such that the key slot will capture the head of pin 40 and will initially slide relative to the auxiliary locking pin without any significant force

being transferred to the pin reaction surface, i.e., the tenon, by the complementary shaped inwardly facing surfaces of groove 60, i.e., the mortise.

Restated, the initial displacement of the mortise defining walls from the keyway side, commensurate with the first slot operational depth, is insufficient to pull pin 40 inwardly.

When the key blade 44 is fully inserted in the keyway 20, i.e., when the condition depicted in Figures 5A and 5B is reached, a ramp portion of slot 60, the section 64 in the disclosed embodiment, will have coacted with the head 46 of pin 40 to pull pin 40 outwardly against the bias of spring 44. Restated, the transition of longitudinal slot 60 from the linear first operational depth portion to the deeper second operational depth portion will cause an axial force to be applied to the reaction surface on the head 46 of pin 40 by the complementary surface which in part defines slot 60. This applied axial force will result in the auxiliary locking pin 40 being at least partially withdrawn from recess 50 in shell 18. In the disclosed embodiment, the cooperation between the head portion of the auxiliary locking pin and slot portion 64 will result in partial withdrawal of pin 40 from recess 50 as depicted in Figure 5A. In this partially withdrawn position, the wall 80 on the pin no longer abuts recess defining wall 82 and the downstream edge of camming surface 54 of pin 40 is thus disposed on the core side of recess side wall surface 82. Restated, the coaction between the slot in the key blade and head of the auxiliary locking pin will impart sufficient axial movement to pin 40, against the bias of spring 44, to discontinue the rotation blocking cooperation between pin 40 and recess 50 and, thereby, enable core rotation. However, when the head 46 of pin 40 has a shaped projection 48, rotation of core 16 relative to shell 18 to the point where the latch coupled to core 16 could be operated will be prevented in the absence of some provision to enable further axial movement of pin 40 away from shell 18. Thus, in the disclosed embodiment, partial withdrawal of the auxiliary locking pin 40 from engagement in recess 50, as depicted in Figures 5A and 5B, does not permit lock operation because full rotation of core 16 is still prevented by interference between a camming surface 70, provided on the inner wall of the shell immediately adjacent wall 82 of recess 50, and an axially immobilized auxiliary

locking pin, i.e., a locking pin that cannot move further in the axial direction into the keyway because the pin extension 48 bottoms in key slot 60.

Referring to Figures 6A and 6B, by providing the aperture 68 in the key blade, the cam surface 70 on shell 18 may cooperate with surface 54 on projection 52 of auxiliary locking pin 40 to produce an axial force which drives the extension 48 on the head 46 of pin 40 into aperture 68 in response to the application of torque to bow 22 of key 20. In the preferred embodiment, iri the unlocked state depicted in Figure 6, at least a portion of the head 46 of auxiliary locking pin 40 extends across the plane of the center of the keyway.

In a lock in accordance with the present invention, the most outwardly disposed surface area(s) of the projecting second end 52 of the auxiliary locking pin, i.e., the camming surface 54 in the disclosed embodiment, are preferably, but are not necessarily, complementary in shape to the inner diameter of shell 18. Also, referring to Figure 2A, the longitudinal slot 60 in the key blade is preferably continued past the location of the auxiliary locking pin and will preferably transition back to at least its initial depth. This extension of slot 60 is in the interest of facilitating the cleaning thereof. As will be obvious to those skilled in the art, it is possible to employ a plurality of the auxiliary locking pins 40. Where a plurality of auxiliary locking pins is employed, they could enter the keyway from opposite sides.

While a preferred embodiment has been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is: